Table 1 Overview of planes, methods, level/side, and scoring

All planes

Overall image quality:

1 = Poor, impossible for visualization of bony structures

N/A

2 = Impaired, difficult for visualization of bony structures

N/A

3 = Good, for visualization of bony structures

4 = Excellent

Paracoronal

Lumbosacral transitional anomaly:

0 = Not present

1 = Present

Paracoronal

Fusion of the growth plates of the sacrum:

Level S1/S2

0 = Open

1 = Partially closed

2 = Completely closed

Level S2/S3

0 = Open

1 = Partially closed

2 = Completely closed

Paracoronal

Cortical delineation of the joint space:

Iliac side (R/L)

0 = Not clearly visible, the iliac joint is not completely seen as a hyperdense cortical line

1 = Clearly visible, the iliac joint is clearly seen as a hyperdense cortical line

Sacral side (R/L)

0 = Not clearly visible, the sacral joint is not completely seen as a hyperdense cortical line

1 = Clearly visible, the sacral joint is clearly seen as a hyperdense cortical line

Paracoronal

Joint facet defect (≥ 3 mm):

Iliac side (R/L)

0 = Not present, no surface defect greater than or equal than 3 mm are present

1 = Present, there is one or more surface defect(s) greater or equal than 3 mm (the measurement of the defect can be parallel or perpendicular to the joint space)

Sacral side (R/L)

0 = Not present, no surface defect greater than or equal than 3 mm are present

1 = Present, there is one or more surface defects greater or equal than 3 mm (the measurement of the defect can be parallel or perpendicular to the joint space)

Paracoronal

Presence of ossified nuclei of the SI joint:

R/L

0 = Not present

1 = Present and not fused

2 = Partially fused ossified nuclei

Paracoronal

Bony bridges of the SI joint:

R/L

0 = Not present

1 = Present